In process systems, analysis of control degrees of freedom (CDOF) is a primary step for control structure design. CDOF is equal to the maximum number of variables that can be independently manipulated by the control system. This study develops a novel approach for systematic computation of CDOF through the identification of topological characteristics of process flow diagrams (PFDs). The analysis has a top-down approach in which the main set of potential manipulated variables (MVs) is decomposed into internal and boundary subsets, then CDOFs for the internal and boundary MVs are determine separately. In order to develop the method, three assisting terms have been introduced: (1) circuit, (2) bypass, and (3) route. The suggested formula computes both dynamic and steady state CDOF using basic information obtained from the plant's PFD. Applicability and reliability of the proposed method have been successfully checked for various case studies ranging from simple units to complex process plants. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.